The sweet pea, ''Lathyrus odoratus'', is a

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nom ...

Lathyrus ''Lathyrus'' is a genus of flowering plants in the legume family Fabaceae, and contains approximately 160 species. Commonly known as peavines or vetchlings, they are native to temperate areas, with a breakdown of 52 species in Europe, 30 spec ...

'' in the

family Family (from la, familia) is a group of people related either by consanguinity (by recognized birth) or affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its members and of society. Idea ...

Fabaceae ( legumes),

native Native may refer to: People * Jus soli, citizenship by right of birth * Indigenous peoples, peoples with a set of specific rights based on their historical ties to a particular territory ** Native Americans (disambiguation) In arts and entert ...

to Sicily, southern Italy and the Aegean Islands. It is an

annual Annual may refer to: *Annual publication, periodical publications appearing regularly once per year ** Yearbook ** Literary annual *Annual plant *Annual report *Annual giving *Annual, Morocco, a settlement in northeastern Morocco *Annuals (band), ...

climbing plant, growing to a height of , where suitable support is available. The leaves are

pinnate Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and in ...

with two leaflets and a terminal

tendril In botany, a tendril is a specialized stem, leaf or petiole with a threadlike shape used by climbing plants for support and attachment, as well as cellular invasion by parasitic plants such as '' Cuscuta''. There are many plants that have tend ...

, which twines around supporting plants and structures, helping the sweet pea to climb. In the wild plant the

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s are purple, broad; they are larger and highly variable in color in the many

cultivar A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...

s. Flowers are usually strongly scented. The annual

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

, ''L. odoratus'', may be confused with the everlasting pea, '' L. latifolius'', a perennial.

Horticultural development

Scottish

nurseryman A nursery is a place where plants are propagated and grown to a desired size. Mostly the plants concerned are for gardening, forestry or conservation biology, rather than agriculture. They include retail nurseries, which sell to the general p ...

Henry Eckford (1823–1905) cross-bred and developed the sweet pea, turning it from a rather insignificant if sweetly scented flower into a floral sensation of the 19th century. His initial success and recognition came while serving as head gardener for the

Earl of Radnor Earl of Radnor, in the County of Wiltshire, is a title which has been created twice. It was first created in the Peerage of England in 1679 for John Robartes, 2nd Baron Robartes, a notable political figure of the reign of Charles II. The ea ...

, raising new cultivars of pelargoniums and

dahlia Dahlia (, ) is a genus of bushy, tuberous, herbaceous perennial plants native to Mexico and Central America. A member of the Asteraceae (former name: Compositae) family of dicotyledonous plants, its garden relatives thus include the sunflower, ...

s. In 1870 he went to work for one Dr. Sankey of Sandywell near Gloucester. A member of the

Royal Horticultural Society The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity. The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr (Nor ...

, he was awarded a First Class Certificate (the top award) in 1882 for introducing the sweet pea cultivar 'Bronze Prince', marking the start of association with the flower. In 1888 he set up his development and trial fields for sweet peas in Wem in

Shropshire Shropshire (; alternatively Salop; abbreviated in print only as Shrops; demonym Salopian ) is a landlocked historic county in the West Midlands region of England. It is bordered by Wales to the west and the English counties of Cheshire to ...

. By 1901, he had introduced a total of 115 of the 264 cultivars grown at the time. Eckford was presented with the RHS Victoria Medal of Honour for his work. He died in 1906, but his work was continued for a time by his son John Eckford. More recently, the association between the sweet pea, the Eckfords and Wem has been highlighted again. In the late 1980s, the Sweet Pea Society of Wem started an annual show. Many of the street signs now carry a sweet-pea motif, and an area of the town is known as Eckford Park. There is also a cultivar 'Dorothy Eckford', named after a family member.

Cultivation

Sweet peas have been cultivated since the 17th century and a vast number of cultivars are commercially available. They are grown for their flower colour (usually in pastel shades of blue, pink, purple and white, including bi-colours), and for their intense unique fragrance. They are grown by gardeners for private enjoyment or for exhibition, and in the

floristry Floristry is the production, commerce, and trade in flowers. It encompasses flower care and handling, floral design and arrangement, merchandising, production, display and flower delivery. Wholesale florists sell bulk flowers and related su ...

trade. The large, pea-shaped seeds are sown in

cold frame In agriculture and gardening, a cold frame is a transparent-roofed enclosure, built low to the ground, used to protect plants from adverse weather, primarily excessive cold or wet. The transparent top admits sunlight and prevents heat escape via co ...

s in Spring or Autumn. The seeds benefit from pre-soaking or chipping with a sharp blade. The plants are also available later in the season, as young plants or plugs. They are grown up canes, with the new shoots being regularly pinched out to promote a bushy habit and higher flower yields. Plants typically reach heights of 1-2m, with the flowers appearing in midsummer and continuing for many weeks if regularly deadheaded. Over 50 cultivars have gained the

's Award of Garden Merit. See List of AGM sweet peas

Pests and diseases

The sweet pea plant does suffer from some pests, the most common being

aphids Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

. These insects suck the sap out of the plants, reducing growth.

Mosaic virus A mosaic virus is any virus that causes infected plant foliage to have a mottled appearance. Such viruses come from a variety of unrelated lineages and consequently there is no taxon that unites all mosaic viruses. All the symptoms of each virus ...

is spread by greenfly, causing yellowing of leaves, distortion of new shoots, and inhibited flowering. A pest called the pollen beetle which is small, shiny and black, eats the pollen and disfigures the flowers. Other pests include caterpillars, thrips, slugs and snails. Another problem is

mildew Mildew is a form of fungus. It is distinguished from its closely related counterpart, mould, largely by its colour: moulds appear in shades of black, blue, red, and green, whereas mildew is white. It appears as a thin, superficial growth consi ...

; this is a white powdery coating that covers the leaves and slows down growth. The sweet pea is also susceptible to ethylene in quantities produced by senescing plants. Because of this, growers are encouraged to plant sweet peas away from fruit trees among other plants prone to early dieback or senescence.

Toxicity

Unlike the edible

pea The pea is most commonly the small spherical seed or the seed-pod of the flowering plant species ''Pisum sativum''. Each pod contains several peas, which can be green or yellow. Botanically, pea pods are fruit, since they contain seeds and d ...

, there is evidence that

seed A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...

s of members of the genus ''Lathyrus'' are toxic if ingested in quantity. A related species, ''

Lathyrus sativus ''Lathyrus sativus'', also known as grass pea, cicerchia, blue sweet pea, chickling pea, chickling vetch, Indian pea, white pea and white vetch,'' Kew GardensLathyrus sativus'' (grass pea) is a legume (family Fabaceae) commonly grown for human ...

'', is grown for human consumption but when it forms a major part of the diet it causes symptoms of toxicity called lathyrism. When sweet peas are planted too close to each other it causes fungal diseases like powdery mildew. Powdery mildew looks like white-silver dust that settles on the plant's leaves, flowers and stems. Fungus suck nutrients from sweet peas and stunt their growth. In studies of rats, animals fed a diet of 50% sweet pea seeds developed enlarged adrenals relative to control animals fed on edible peas. The main effect is thought to be on the formation of collagen. Symptoms are similar to those of

scurvy Scurvy is a disease resulting from a lack of vitamin C (ascorbic acid). Early symptoms of deficiency include weakness, feeling tired and sore arms and legs. Without treatment, decreased red blood cells, gum disease, changes to hair, and bleeding ...

and copper deficiency, which share the common feature of inhibiting proper formation of collagen fibrils. Seeds of the sweet pea contain

beta-aminopropionitrile Aminopropionitrile, also known as β-aminopropionitrile (BAPN), is an organic compound with both amine and nitrile functional groups. It is a colourless liquid. The compound occurs naturally and is of interest in the biomedical community. Biochem ...

that prevents the cross-linking of collagen by inhibiting

lysyl oxidase Lysyl oxidase (LOX), also known as protein-lysine 6-oxidase, is an enzyme that, in humans, is encoded by the ''LOX'' gene. It catalyzes the conversion of lysine molecules into highly reactive aldehydes that form cross-links in extracellular matr ...

and thus the formation of allysine, leading to loose skin. Recent experiments have attempted to develop this chemical as a treatment to avoid disfiguring skin contractions after skin grafting.

Genetics

Gregor Mendel Gregor Johann Mendel, OSA (; cs, Řehoř Jan Mendel; 20 July 1822 – 6 January 1884) was a biologist, meteorologist, mathematician, Augustinian friar and abbot of St. Thomas' Abbey in Brünn (''Brno''), Margraviate of Moravia. Mendel was ...

is today recognized as the "Father of Modern Genetics" for his work with the cross breeding of

plants (''

Pisum sativum The pea is most commonly the small spherical seed or the seed-pod of the flowering plant species ''Pisum sativum''. Each pod contains several peas, which can be green or yellow. Botanically, pea pods are fruit, since they contain seeds and d ...

'') with different characteristics, and sweet pea has been used in a similar way. The sweet pea is thus a model organism being used in early experimentations in genetics, particularly by the pioneer geneticist

Reginald Punnett Reginald Crundall Punnett FRS (; 20 June 1875 – 3 January 1967) was a British geneticist who co-founded, with William Bateson, the ''Journal of Genetics'' in 1910. Punnett is probably best remembered today as the creator of the Punnett ...

. It is highly suitable as a genetic subject because of its ability to self-pollinate and its easily observed Mendelian traits such as colour, height and petal form. Many genetic principles were discovered or confirmed in this species. It was used by Punnett in early studies of genetic linkage. Complementary factor inheritance was also elucidated in sweet peas, from the cross of two pure-breeding white strains which gave rise to a blue hybrid, the blue colour requiring two genes derived independently from the two white parents.

Hybridization with ''Lathyrus belinensis''

Like the

blue rose A blue rose is a flower of the genus ''Rosa'' (family Rosaceae) that presents blue-to-violet pigmentation instead of the more common red, white, or yellow. Blue roses are often used to symbolize mystery or attaining the impossible. However, beca ...

, the yellow sweet pea remains elusive. '' Lathyrus belinensis'' is a related Lathyrus species which has red and yellow flowers. There are ongoing attempts to bring the yellow color into ''Lathyrus odoratus'' by crossing it with ''Lathyrus belinensis''. Several new sweet pea cultivars have been created as a result, though not any with the yellow flower color so far.Dawn Edwards
''Developing a yellow sweet pea''
/ref>

Gallery

File:Sweet Pea-1.jpg File:Sweet Pea-3.jpg File:Sweet Pea-6.jpg File:Sweet Pea-5.jpg File:Sweet Pea-2.jpg File:Sweet Pea-4.jpg File:Sweet Pea-7.jpg

References

{{Authority control Lathyrus Annual plants Vines Garden plants Garden plants of Europe Plants described in 1753 Nitrogen-fixing crops